Relay apparatus



1960 R. P. BENNETT ,95

RELAY APPARATUS Filed June 24, 1958 3 Sheets-Sheet 1 INVENTOR. ROBERT P. BENNETT Sin aim ana a oim ATTORNEYS 5, 9 R. P. BENNETT 2,957,966

RELAY APPARATUS Filed June 24, 1958 3 Sheets-Sheet 2 "'IIII INVENI OR.

ROBERT F! BENNETT 3.: .1 U. BY

Sapim and SAa uro A TTOR/VE Y5 Oct. 25, 1960 R. P. BENNETT 2,957,966

RELAY APPARATUS Filed June 24, 1958 S Sheets-Sheet 3 4 16 los 68 88 26 5 58 T P88 5 l8 Y94 I: E -1 S5 INVENTOR.

ROBERT P. BENNETT sfia iro and Swim A TTORNE Y5 RELAY APPARATUS Robert P. Bennett, 509-Wilson Place, Frederick, Md;

Filed June 24, 1958, Ser. No. 744,127

11 Claims. (Cl. 200-'105) This invention relates to improved relay apparatus, and more particularly to novel relay structure and circuits.

It has been found that the current rating of relay switch contacts may be increased substantiaily by increasing the speed with which the contacts are transferred and that by providing extremely fast transfer of contacts relatively large currents may be accommodated without appreciable deterioration of the contacts. As the size of the relay is decreased, however, it becomes increasingly diflicult to obtain the desired speed of operation along with reliability and long life. The problems are accentuated when the relay is subjected to vibration and extreme temperature changes in the course of its operation.

It is a primary object of the present invention to provide a small, versatile, inexpensive relay that is inherently fast-acting and efficient.

Another object of the invention is to provide an improved relay having the foregoing desirable characteristics and yet which is operable from low power level sources.

A further object of the invention is to provide such a relay which" is operable by low energy level pulses, as for usewith remote controlled television sets and signal lights.

An additional object of the invention is to provide a relay of the foregoing type in which the contacts are held mechanically and positively in either closed or open position when the relay is de-energized and in which successive energizations of the relay transfer the contacts between open and closed'positions.

A still further object of the invention is to provide such a relay in which the contacts are maintained in position without energy consumption.

Yet another object of the invention is to provide a relay of the foregoing type which includes a' unique pawl and ratchet mechanism requiring but one coil.

A still further object of the inventionis to provide a relay of the foregoing type having long life. ensured through virtually friction-free operation.

An additional object of the invention is to provide a relay of the foregoing type that is highly resistant to shock and vibration, and that is operable throughout a wide temperaturerange.

Still another object of the invention is to provide unique relay sub-assemblies.

A further object of the invention is to provide an improved relay which may be operated manually.

Another object of the invention is to provide an improved relay having a first switch with cam-operated latching contacts and a second switch with non-latching contacts.

Stillanother object of the invention is to provide an improved relay having two cam-operated switches, the arrangement being such that the force required to transfer the contacts is substantially the same for successive energizations of the relay.

An additional object of the invention is to provide improved relay circuits and pulse actuated relay apparatus.

The foregoing and other objects, features, and advantages of the invention and the exact manner in which the same are accomplished will become more readily apparent upon consideration of the following detailed description of exemplarly forms of the invention when 2,957,966 Patented Oct. 25, 1960.

taken in conjunction with the accompanying drawings which illustrate such forms and wherein:

Figure 1 is a side elevation view of a basic form of relay unit of the invention illustrating its adaptation to manual actuation;

Figure 2 is a reverse side elevation view of the form of Figure 1;

Figure 3 is a top plan view of the same form of the invention;

Figure 4 is an end elevation view of the same form;

Figure 5 is an enlarged side elevation View of a detail of the invention;

Figure 6 is a perspective view of a sub-assembly of the invention;

Figure 7 is a schematic diagram of one form of circuit employed in accordance with the invention;

Figure 8 is a side elevation view of another form of relay unit of the invention;

Figure 9 is an end elevation view of the same form of the invention;

Figure 10 is a perspective view of a sub-assembly of the last-mentioned form;

Figure l l is a side elevation view of another form of relay unit of the invention;

Figure 12 is an end elevation viewof this form;

Figure 13 is a schematic diagram of another form of circuit employed in accordance with the invention; and

Figure 14 is a schematic diagram of still another form of circuit employed in accordance with the invention.

Referring to the drawings, and at first to Figures 1 through 4 thereof, a basic form of the invention concerns a relay 10 having a coil frame 12 which is preferably of L-shaped configuration. The coil frame has a major leg 14 and a minor leg 16. These legs embrace an electromagnet coil 18 which maybe supported on the frame as by a single screw 20 (Figure 4) which passes through the leg 16 of the frame and is threaded into the core of the coil. The coil is of conventional construction, comprising the core, a helical winding of wire (the gauge and number of turns being determined by the required current rating and magnetic field strength), a fabric covering, and fiber end discs 19 and 21. Disc 21 may be flattened at one edge portion so as to rest on the frame to steady the coil. Terminals 23 are attached to the winding ends to adapt the coil for connection to an energization circuit. As shown in Figure 4, the frame is preferably provided with threaded bores 22 by which the frame may be attached to a main panel or chassis. The electromagnet has a pole piece 24 adjacent which is located an armature 26, which is preferably of the clapper type as shown in Figure 6. The upper part of the armature is notched as shown at 28 so that the armature may be supported on forward extensions 30 at the end of the frame leg 14 remote from the leg 16. As shown in Figure l, the notches 28 are made wider than the thickness of the frame so that the armature may have limited pivotal movement on the frame. The armature is held in position on the frame by a thin resilient retainer plate 32 (best seen in Figure 3) having a lip 34 which depends in front of the armature.

As shown in Figure 6, the armature 26 has a'pair of arms 36 and 38' (preferably formed integrally therewith) which extend in substantially the same direction from opposite edges of the armature. Arm 36 is provided with a projection 40 which engages the under surface of a leaf-type armature return spring 42 best seen in Figures 2 and 3. The return spring is aflixed to the side of the frame opposite the coil 18 as by screws 44. As shown in Figure 2, the return spring is bent downwardly so as to exert a force on the projection 40 and thereby urge the armature 26 away from the pole piece 24.

The lower edge of the arm 36 is engaged by a stop member 46 which depends from a thin supporting plate 48 (Fig. 3) also secured to the frame by screws 44. The position of the stop member 46 determines the maximum extent of movement of the armature 26 away from the pole piece 24.

Arm 38 is provided with a pawl 50 which is freely pivoted on the arm adjacent one end thereof, as by a pivot pin 52 which passes through the base of the pawl and is secured to the arm 38. The pawl has a pair of resilient arms 54 and 56, one of which is longer than the other, as shown. These arms, which in the form shown are formed integrally with and bent substantially perpendicular to the base of the pawl, embrace a ratchet wheel 58 as best seen in Figure 5. The shorter arm, 54, is arranged to enter between the teeth of the ratchet wheel so as to advance them, the tip of the arm engaging the radial surface of each tooth in succession. The longer arm, 56, merely lies adjacent the tips of the teeth. This arrangement permits the pawl to be freely pivoted on arm 38 and yet to remain properly positioned with respect to the ratchet wheel. Arm 56 applies a very slight frictional force to the ratchet wheel to maintain the arm 54 in proper position, and at the same time, the frictional force exerted by arm 56 clamps the movement of the ratchet wheel so that there is no tendency of the ratchet wheel to rotate reversely, to vibrate, or to overrun.

The ratchet wheel 58 is rotatably supported on the coil frame as by a screw 60 threaded into the free leg of an angle bracket 62 best seen in Figure 4. The angle bracket may be fixed to the frame by screws 64 (Fig. 3) which pass through the insulators of a relay switch stack 66 to be described in detail hereinafter.

Affixed to the ratchet wheel 58, and preferably formed integrally therewith, is a cam 68. The cam and ratchet wheel may be formed of nylon. The cam rotates with the ratchet wheel and has alternate high and low regions as best seen in Figure 5. The cam engages the contact operating arm 70 of the switch stack 66, and the contact operating arm is spring biased against the cam, preferably by its inherent resiliency. The contact operating arm 70 carries moving contacts 72 which are arranged to engage alternately stationary contacts 74 and 76 supported on the contact leaves 78. The contact leaves and the contact operating arm (which have terminals 83) are in turn separated and supported by stacked insulators 80 capped by a metal plate 82 into which the screws 64 are counter-sunk. The screws pass through the insulators and hold the whole assembly on the frame.

The high and low regions of cam 68 are mated with the teeth of the ratchet wheel 58 such that for the movement of the ratchet wheel by one tooth the engagement of the cam with the contact operating arm 70 is changed from a high region to a low region, and so forth as the teeth are advanced successively. When a high region engages the contact operating arm as shown in Figure 5, contact 72 engages contact 74, and when a low region of the cam engages the contact operating arm as shown in Figure 1, contact 72 engages contact 76. Thus as the ratchet Wheel is advanced tooth-by-tooth, the switch 66 transfers from a closure of one set of contacts to a closure of the other set of contacts, the switch being latched in successive positions by the cam and by the spring baised contact operating arm. The arrangement is such that the ratchet wheel is advanced one tooth each time the armature 26 approaches the pole piece 24.

The switch contacts may be transferred by manual actuation, as by providing a push button 84 adjacent the armature 26, as shown in Figure 1. The push button is mounted in a panel 86 and preferably has its own return spring. When the button is depressed, the armature is moved toward the pole piece 24. The pawl 50 moves upward, advancing the ratchet wheel one tooth,

and the switch contacts are transferred. When the button is released, the armature returns to its rest position under the impetus of the armature return spring, and the pawl moves downward to its rest position. In moving downward, arm 54 slides on the sloping portion of the next tooth, springing the arms 54 and 56 farther apart so as to increase the damping force of arm 56 until arm 54 snaps behind the radial portion of the tooth.

The manual actuation is normally an adjunct to electrical actuation, and a preferred actuating circuit is illustrated in Figure 7, in which the elements of the switch stack 66, the cam 68, the ratchet wheel 58, the pawl 50, and the armature 26 are shown diagrammatically. The coil 18 is arranged to be energized from a source of electric potential 88 shown as a battery. The battery is connected in a series circuit with a resistor 90 and a condenser 92, this circuit constituting a charging circuit for the condenser. A discharging circuit for the condenser is provided by the coil 18 which is connected across the condenser through a switch 94. A master switch (not shown) may be provided in the charging circuit. When the charging circuit is closed, the condenser 92 charges, and after a length of time determined by the time constant of the charging circuit, the condenser is fully charged to the potential of the source 88. If switch 94 is then closed, the condenser will discharge through the coil 18, and a pulse of energy will be applied to the coil to operate the ratchet mechanism and transfer the switch contacts. The shape of the pulse applied to the coil is dependent upon the parameters of the discharging circuit. When switch 94 is opened, the condenser 92 will re-charge, and the relay apparatus will be ready for another transfer of contacts.

The apparatus of the invention is capable of very fast switching. In one practical embodiment the switching time was within 1 /2 milliseconds of the time constant of the discharge circuit. Such extremely fast switching increases the usual contact rating by from 3 to 10 times. An important characteristic of the apparatus of the invention is its ability to handle relatively high currents and yet maintain its compactness. In a practical form of the invention, the relay unit has an overall length of 1.62 inches, a width of 1.06 inches, and a height of 1.56 inches. The total weight of the relay is 1 /2 ounces. Yet the contacts, which may be of palladium, gold, or silver, for example, are capable of handling regular loads of 7 /2 amps, 115 volts A.C. resistive, for example, with a contact pressure of 50 grams minimum. The operating speed is 3.5 milliseconds for a .15 watt-second pulse. Thus it is apparent that fast operation is obtainable from low energy sources. Such a unit will operate a minimum of 1 million times at rated load and will continue to op erate satisfactorily even when subjected to vibrations of 5 to 55 cycles per second at .200 inches excursion, for example, and to temperature changes within the range of minus 65 degrees C. to plus degrees C.

The breakdown voltage in a typical unit is 600 volts R.M.S. minimum coil-to-ground and 1000 volts R.M.S. minimum contacts-to-ground. The coil may have any D.C. resistance up to 20,000 ohms, for example, and may have an A.C. rating of 6 volts to 220 volts at 60 cycles. A typical coil may have a power rating of .03 watt-second pulse or 1.8 watt continuous.

The switch of the relay unit as described so far is a single pole double throw type. Other switch elements may be stacked above those shown to control multiple circuits or to form plural pole switches. In the arrangement illustrated in Figures 8 through 10, wherein parts previously described or similar thereto are designated by the same or similar reference numerals, the contact operating arm 70a of an upper switch 66a is operated from the contact operating arm 70 of the lower switch by an insulating button 96 which projects upwardly from arm 70. Thus both switches are operated in unison. Moreover, this embodiment of the invention illustrates the provision of a second stack of cam-operated switches, these switchesv being deisgnated 66b and 66c in Figure 9. The second switch stack is substantially identical to the first and is operated by a second cam 68a. This cam and cam 68 are keyed, splined, or otherwise fixed to a shaft 98 rotatably supported on a U-shaped bracket 100. Bracket 100 must be positioned so as topermit the shaft 98 to clear the insulators 80. In this embodiment screw 60 may rotate with the shaft 98, rather than serve as a stationary pivot pin.

As shown in Figure 10, cam 68a is mated with cam 68 such that the low regions of the former are paired with the high regions of the latter, and vice versa. It is thus apparent that the contact operating arm of switch 66b engages a low region of cam 68a when the contact operating arm of switch 66 engages a high region of cam 68. The same ratchet wheel 58 operates both cams. A significant characteristic of this arrangement is that the structure is balanced, so that substantially the same force is required to accomplish each successive transfer of contacts, since one of the cams moves from a low region to a high region when the other cam moves from a high region to a low region.

The switches may be grouped in a load circuit to provide plural pole switches, or the switches may be connected in separate circuits. The same circuit of Figure 7 may be employed to operate the relay of Figures 8 through 10, and except for the differences noted, the relay of Figures 8 through 10 may have substantially the same characteristics as the relay of Figures 1 through 5.

Figures 11 and 12 illustrate another modification of the relay. In this embodiment one switch stack is camoperated and latching and may be like the corresponding stack of Figurel or Figure 8, and a second switch stack located adjacent the first is a simple momentary contact stack operated directly from the relay armature. As shown, the second switch stack is actuated by a button 102 depending from the contact operating arm 70d of lower switch 66d and moved by the projection 40 on the armature arm 36 with the return. spring 42 interposed between the projection and the button. An upper switch 66e may be operated by a button 104 depending from its operating arm 70a and engaging the upper surface of operating arm 70d. With this arrangement the cam-operated switch 66 is self-latching,while the switches 66d and 66e are operated momentarily upon movement of the armature 26 toward and away from pole piece 24. Except for the differences noted, the embodiment of Figures 11 and 12 may have substantially the same characteristics as the previously described relays.

Figure 13 illustrates an alternative energization circuit employing the elements of the circuit of Figure 7. In this circuit the resistor 90 is connected in shunt with the condenser 92, and the switch 94 is connected in the charging circuit. When the switch is closed, the relay is operated by the in-rush of current through the condenser. When the switch is opened, the condenser discharges through the resistor, and the circuit is ready to operate the relay again upon reclosure of the switch.

Figure 14 illustrates another energization circuit modification in which one relay switch forms a part of the energization circuit. In this circuit one terminal of the battery 88 is connected to a terminal of the coil 18, the other terminal of the coil being connected to the switch blade 70. Contacts 74 and 76 are connected to the corresponding contacts 107 and 109 of a separate single pole double throw switch 106, the blade of which is connected to the remaining terminal of the battery 88. The relay also includes a second switch 67. This switch may be operated by cam 68, as is switch 66a previously described, or may be operated directly from the armature, as is switch 66d previously described. The switch is provided for connection to an external load circuit.

In the operation of the circuit of Figure 14, when switch 106 is closed on contact 107, a circuit for energizing the coil 18 will be completed through contact 74, and the relay will transfer its contacts, thereby breaking the energization circuit. Contact 76 will now engage the switch blade, and if switch 106 is thrown to its alternate position closed on contact 109, the relay will again be energized and will transfer its contacts back to the position illustrated. Successive operations of the relay are thus obtained by operating switch 106 between its alternate contacts.

From the foregoing description it will be apparent to those skilled in the art that the present invention provides unique and improved relay apparatus. While there have been shown and described what are now believed to be preferred embodiments of the invention, it is apparent that changes can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims. Accordingly, the foregoing embodiments are to be considered illustrative, rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalency of the claims are to be included therein.

The invention claimed is:

1. A relay comprising a coil frame, an electromagnet coil mounted on said frame and having an associated armature, a return spring urging said armature away from said coil, a ratchet pawl having a base pivotally connected to said armature, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam mounted for rotation with said ratchet wheel, and a switch mounted on said frame and having a contact operating arm engaging said cam, said ratchet pawl having a pair of unitary arms extending from its base in the same direction and embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said pawl base, but the other of said pawl arms merely engaging the tips of said teeth.

2. A fast-acting miniature relay comprising a coil frame, an electromagnet coil mounted on said frame and having an armature pivoted on said frame, a return spring on said frame urging said armature away from said coil, an arm extending from said armature and provided with a ratchet pawl having a base freely pivoted on said arm, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam fixed to said ratchet wheel, and a switch mounted on said frame and having a spring biased contact operating arm engaging said cam, said ratchet pawl having a pair of unitary arms extending from its base in the same direction and embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said pawl base, but the other of said pawl arms merely engaging the tips of said teeth.

3. A fast-acting miniature relay comprising a coil frame, an electromagnet coil mounted on one side of said frame and having an armature pivoted on said frame near one end thereof, a return spring on said frame urging said armature away from said coil, an arm extending from said armature along said coil and provided with a ratchet pawl having a base freely pivoted on said arm, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam fixed to said ratchet wheel, a switch mounted on the opposite side of said frame and having a spring biased contact operating arm engaging said cam, said ratchet pawl having a pair of unitary arms extending from its base in the same direction and embracing said ratchet wheel, one of said pawl arms being shorter than the other and being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said pawl base, the other of said pawl arms merely engaging the tips of said teeth,

and a push button mounted adjacent said armature and arranged to move the same toward said coil upon manual actuation.

4. A fast-acting miniature relay comprising an L-shaped coil frame, an electromagnet coil mounted on and embraced by said frame and having a clapper type armature pivoted on said frame adjacent one end of said coil to complement the frame portion adjacent the other end, a return spring mounted on said frame near one edge thereof and engaging an arm extending from one side of said armature to urge said armature away from said coil, another arm extending from the other side of said armature and having a ratchet pawl freely pivoted thereon, a stop for limiting the movement of said armature away from said coil, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam fixed to said ratchet wheel, and a switch mounted on said frame opposite said coil and having a spring biased contact operating arm engaging said cam, said ratchet pawl having a pair of arms embracing said ratchet wheel, one of said pawl arms being shorter than the other and entering between the teeth of said ratchet wheel to advance them, the other of said pawl arms being adjacent the tips of said teeth.

5. A relay comprising a coil frame, an electromagnet coil mounted on said frame and having an associated armature, a return spring urging said armature away from said coil, a ratchet pawl connected to said armature, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a first cam mounted for rotation with said ratchet wheel, a first switch mounted on said frame and having a contact operating arm engaging said cam, a second cam mounted for rotation with the first cam, and a second switch mounted on said frame and having a contact operating arm engaging said second cam, said cams having high regions and low regions, the high regions of one cam being paired with the low regions of the other cam, said pawl being U-shaped with its bight pivotally connected to said armature and its arms embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face said bight, and the other of said pawl arms merely engaging the tips of said teeth.

6. In apparatus of the type described, an electromagnet coil, an armature mounted adjacent said coil and arranged to be moved by the magnetic field of the coil, a pawl having a base pivotally connected to the armature, and a ratchet wheel adjacent the pawl, said pawl having a pair of unitary arms extending in the same direction from its base and embracing the ratchet wheel, one of the arms being a driving arm with its tip entering between the teeth of the wheel and engaging the driving surfaces of said teeth which face said base, and the other arm merely engaging the tips of the teeth.

7. The apparatus of claim 6, the first-mentioned arm being shorter than the other.

8. A relay sub-assembly comprising a clapper type armature having a pair of arms extending in the same direction from its opposite sides, one of said arms having a pawl pivoted freely thereon adjacent its free end and adapted to engage a ratchet wheel, the other of said arms being adapted to engage a return spring for the armature, said pawl having a pair of spaced resilient arms extending generally in the same direction, one of which arms is longer than the other.

9. A relay comprising a coil frame, an electromagnet coil mounted on one side of said frame and having an associated armature, a return spring urging said armature away from said coil, a ratchet pawl having a base pivotally connected to said armature, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam mounted for rotation with said ratchet wheel, a switch mounted on the opposite side of the said frame and having a contact operating arm biased into engagement with said cam, said ratchet pawl havinga pair of unitary arms extending from its base in the same direction and embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said pawl base, but the other of said pawl arms merely engaging the tips of said teeth, said cam having alternate high and low regions mated with the teeth of said ratchet wheel such that the advancement of said ratchet wheel tooth-by-tooth changes the engagement of said operating arm with said cam from a high region to a low region successively, whereby said switch is mechanically latched.

10. A relay comprising a coil frame, an electromagnet coil mounted on one side of said frame and having an associated armature, a return spring urging said armature away from said coil, a ratchet pawl having a base pivotally connected to said armature, a ratchet wheel rotatably mounted on said frame and located to be engaged by said pawl, a cam mounted for rotation with said ratchet wheel, a first switch mounted on the opposite side of the said frame and having a contact operating arm biased into engagement with said cam, said ratchet pawl having a pair of unitary arms extending from its base in the same direction and embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said base, but the other of said pawl arms merely engaging the tips of said teeth, said cam having alternate high and low regions mated with the teeth of said ratchet wheel such that the advancement of said ratchet wheel tooth-by-tooth changes the engagement of said operating arm with said earn from a high region to a low region, successively, whereby said switch is mechanically latched, and a second switch mounted on said frame adjacent the first switch, the second switch having a contact operating arm connected for movement with said armature, whereby the second switch transfers its contacts momentarily with movement of said armature.

11. A relay switch actuator or the like, comprising a pawl and ratchet wheel mechanism including a ratchet wheel and a pawl having a base freely pivoted on an actuating arm adjacent the ratchet wheel for movement in the plane of the wheel, the pawl having a pair of resilient arms extending in substantially the same direction from said base and embracing said ratchet wheel, one of said pawl arms being a driving arm with its tip entering between the teeth of said ratchet wheel and engaging the driving surfaces of said teeth which face toward said base, and the other of said pawl arms merely engaging the tips of the teeth, whereby said ratchet wheel is turned when said pawl base approaches said wheel and whereby damping of the wheel movement is accentuated by the spreading of the resilient pawl arms when the pawl base moves away from said wheel.

References (Iited in the file of this patent UNITED STATES PATENTS 941,777 Hart Nov. 30, 1909 1,183,135 Stolp May 16, 1916 2,279,849 Warrington Apr. 14, 1942 2,324,844 Hutt July 20, 1943 2,384,195 Puleo et a1. Sept. 4, 1945 2,547,998 Brockway Apr. 10, 1951 2,562,390 Popp July 31, 1951 2,567,018 Grob Sept. 4, 1951 2,594,670 Mawney Apr. 29, 1952 2,613,791 Triman Oct. 14, 1952 2,627,562 Cataldo Feb. 3, 1953 2,653,200 Foster et al. Sept. 22, 1953 2,695,336 Sengebusch Nov. 23, 1954 2,823,278 Carlson Feb. 11, 

